Field of the Invention
The present invention relates to a technique for mechanically or electronically correcting an image blur in an image capturing apparatus.
Description of the Related Art
In recent years, the number of pixels of an image capturing apparatus capable of capturing moving images is rapidly increasing. Image capturing apparatuses that capture full HD sized moving images are already in wide use, and image capturing apparatuses capable of capturing 4K moving images are also gradually coming into the market. Furthermore, technical development is also underway for 8K super high vision broadcasting which is expected to be available in the future.
With such a trend toward higher definition moving images, with respect to the technique for correcting an image blur in an image capturing apparatus, demand is growing for a highly accurate technique for correcting a finer image blur. Various proposals have been conventionally made on image stabilization function of correcting a blur in a captured image. For example, Japanese Patent Laid-Open No. 2009-152802 discloses a technique in which motion vector information of video detected by an image capturing apparatus is recorded together with a video signal, and image stabilization processing is performed when the video is played back.
However, the following problem arises in a motion vector detection circuit used to detect an image blur in the above-descried conventional technique if the image size of the video signal increases.
A motion vector is detected by, in the case where an image has a characteristic shape such as an edge, computing a positional change on an image of the characteristic shape between the current frame image and the past frame image. Accordingly, a detection area in the image where a motion vector is detected is required to have a size enough to include the characteristic shape of the image. A small detection area brings about a deterioration in the accuracy of motion vector detection. A moving image having a large image size has, as compared to a moving image having a small image size, a greater number of pixels in an image area including an object of the same size. For example, when a full HD (1920×1080 pixels) sized moving image is compared with a 4K (3840×2160 pixels) moving image, the number of pixels increases four times, and when it is compared with a 8K (7680×4320 pixels) moving image, the number of pixels increases sixteen times, which inevitably leads to an increase in the circuit scale and an increase in the power consumption caused by the increase in the circuit scale.